Federal Republic of Germany Patent No. DE 29 51 094, expressly incorporated herein by reference, relates to a gripper for the grasping, moving and/or transporting of preferably round and/or tubular articles. This known gripper has a plurality of gripper elements which grip the article on the inside and/or outside surfaces thereof and are mounted for rotation on a frame by external levers. The mounting pins of the external levers are fastened in a rotationally fixed manner, to an inner lever, which is connected by a gearing mechanism with a setting member connected with a drive unit in such a manner that all of the gripper elements are movable either annularly in the same direction and simultaneously concentrically towards the center of the gripper or, in likewise manner, towards the outside. With this gripper device it is possible, for example, to grip at several locations on its inside or outside surface of a ring heated to a forging temperature and transport it. It is essential, in this connection, in view of the deformability and stiffness of the workpiece to be gripped, that the number of gripper elements be as large as possible. The larger number of grippers, in such a case more uniformly distribute a gripping force.
The device of DE 29 51 094 presents the disadvantage that the stop surface of the device on the body to be gripped is eccentric so that dependable grasping of the body simultaneously by all gripper elements is not assured, since an oblique position of the device is not excluded. Furthermore, the article gripped cannot be turned by the gripper mechanism according to DE 29 51 094.